Tube punching and collaring system, device and method

ABSTRACT

A tube punching system for punching at least one hole into a tube, said system comprising: a punch, an external mold and a counter die. The mold and punch are positioned relative to each other such that the mold exerts a counterforce onto the tube when the hole is punched; and wherein the mold subsequently forms a collar as a result of the force applied by punch against the tube.

FIELD OF THE INVENTION

The invention relates to punching and collaring technology of tubes.More specifically, the present invention relates to tubes that may beused in solar heating, air conditioning and fluid conduction systems.

BACKGROUND OF THE INVENTION

Tubes that have a plurality of holes punched therein are in widespreadusage as manifolds in many products such as solar heating panels.

In the art, several systems are in use enabling punching of holes intothe wall of a tube.

In the art, an acceptable direction of punching is from the inner sideof the tube to the outer side of the tube. Such a type of punching ishereinafter referred to as “punching a hole into a tube”.

However, in order to use such tubes as manifolds, the punching of holesinto the tubes should preferably generate a collar around each hole tofacilitate brazing of other tubes onto the tube manifolds.

The structure of the collar determines the quality of the brazinginterface between the tube manifold and the parts thereon.

A known technique is making the hole and collar by a T-drill machine,developed by a company named T-drill. The machine drills the hole andmakes the collar by turning fingers. The result is good but the processis slow and expensive due to tooling wear.

Another common technique is punching the tube from inside outwards, by apunch having smaller diameter cutting edge than the punch body diameter.The punch is forced out through the tube wall, and creates hole withcollar. Such machine is made by Coilco from USA. The result of thisprocess is good in production rate and tooling cost, but does not bringquality collar: the collar is conical and thus, does not assure brazingstrength. Moreover, brazing material volume is relatively high.

It is an object of the invention to provide a way to punch tube and makequality collar in a more economic process.

Advantage of such a whole structure is in brazing manifold tubereliability and strength as well as in brazing material saving.

It is also an object of the invention to provide a novel way of scrapcutoff and removal off the machine. Scrap falls down unlike existingmachines in which it falls around the punching point.

SUMMARY OF SOME EMBODIMENTS OF THE INVENTION

The present invention relates to a machine that combines a highlyefficient punching method with a system and/or device that providesquality collar.

Generally speaking, a collar is examined by the similarity to acylindrical shape, i.e., the similar a collar to a cylinder, the betteris the quality of the collar, since a substantially cylindrical collarfacilitates brazing of tubes on said collar.

It is to be understood that the term “punching a hole into a tube” orgrammatical variations thereof, refer to a method wherein the directionof the punching is from the inner side of the tube to the outer side ofthe tube.

According to an embodiment of the invention, the present inventionprovides a method for punching at least one hole in a tube comprisingthe steps of: providing a system comprising a punch and a mold, placingthe tube on the system such that the tube extends along a system axis,the punch is located within the tube and the mold is located outside ofthe tube, biasing the punch along a punch axis which is transverse tothe system axis to make a hole in a wall of the tube, wherein at least aportion of the wall adjacent the hole is pressed between the punch andthe mold to form a collar.

In some embodiments, the punch has an inclined surface. The punch isoperated by a push bar having a surface that is substantially equal tothe inclined surface of the punch.

In embodiments of the invention, the movement of the push bar is enabledby an external drive and by moving the push bar the punch is movedoutwardly. The push bar is axially displaced towards the punch, suchthat an inclined surface of said push bar slides over the punch andthereby exerts a force onto the punch such that the punch is displacedin a direction which is substantially perpendicular to the displacementof the push bar.

In embodiments of the invention, the push bar may be propelled by, forexample, a mechanical, a pneumatic, a hydraulic, and an electric or anyother suitable drive.

In some embodiments of the invention, the collar is formed about thepunch axis.

In some embodiments of the invention, during the biasing of the punch tomake the hole the mold at least partially abuts the wall of the tubefrom the outside.

In some embodiments of the invention, the mold comprises a cavity thatextends along the punch axis and opens out towards the tube, wherein atleast a portion of the punch enters the cavity when making the hole inthe tube.

In some embodiments of the invention, the at least portion of the walladjacent the hole that forms the collar is pressed between the punch andthe cavity of the mold.

In some embodiments of the invention, the system comprises a counterdie, at least a position of the counter die being located within thecavity of the mold.

In some embodiments of the invention, the system comprises a biasingmeans that constantly biases the counter die towards the tube.

In some embodiments of the invention, at least a portion of the wall ofthe tube is pressed between the punch and the counter die when formingthe hole.

In some embodiments of the invention, the external faces of the collarand tube merge via a radius wherein in a cross section including thesystem and punch axes the radius is optionally smaller than 1millimeter, preferable smaller than 0.8 millimeter and furtherpreferably smaller than 0.5 millimeter.

According to an embodiment of the invention, the present inventionprovides a system for forming at least one hole in a tube, the systemcomprising a punch and a mold, the tube when placed on the systemextending along a system axis, the punch being located within the tubeand being adapted to move along a punch axis that is transverse to thesystem axis, the mold being located outside of the tube and comprising acavity that extends along the punch axis.

In some embodiments, the system comprises a counter die wherein at leasta portion of the counter die is located within the cavity,

In some embodiments, the system comprises a biasing means thatconstantly biases the counter die towards the tube.

In some embodiments, the punch comprises an elliptical cutting edgewherein the major axis of the ellipse extends along the system axis.

In some embodiments, the mold is adapted to be biased towards and awayof the tube.

In some embodiments, the counter die comprises a cavity extending alongan axis substantially coaxial with the punch axis.

In some embodiments, the punch comprises a cutting edge, the cuttingedge being adapted to be received within the cavity of the counter die.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention will become more clearlyunderstood in light of the ensuing description of embodiments thereof,given by way of example only, with reference to the accompanyingdrawings, wherein

FIG. 1 is a schematic perspective front sectional view of a portion of apunching system that includes punching tools for punching a tube,wherein the punching tools are positioned adjacent the tube;

FIG. 2 is a side sectional view of the system during punching andcollaring a tube;

FIG. 3 is an enlarged side view of the system during punching;

FIG. 4 is a schematic sectional side view of the system;

FIG. 5A is a schematic sectional side view of a punched tube; and

FIG. 5B is a schematic sectional front view of a punched tube.

The drawings taken with description make apparent to those skilled inthe art how the invention may be embodied in practice. It should beunderstood that no attempt is made to show structural details of theinvention in more detail than is necessary for a fundamentalunderstanding of the invention.

It will be appreciated that for simplicity and clarity of illustration,elements shown in the figures have not necessarily been drawn to scale.For example, the dimensions of some of the elements may be exaggeratedrelative to other elements for clarity. Further, where consideredappropriate, reference numerals may be repeated among the figures toindicate corresponding or analogous elements.

DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

An embodiment is an example or implementation of the inventions. Thevarious appearances of “one embodiment,” “an embodiment” or “someembodiments” do not necessarily all refer to the same embodiments.

Although various features of the invention may be described in thecontext of a single embodiment, the features may also be providedseparately or in any suitable combination. Conversely, although theinvention may be described herein in the context of separate embodimentsfor clarity, the invention may also be implemented in a singleembodiment.

Reference in the specification to “one embodiment”, “an embodiment”,“some embodiments” or “other embodiments” means that a particularfeature, structure, or characteristic described in connection with theembodiments is included in at least one embodiment, but not necessarilyall embodiments, of the inventions.

It is understood that the phraseology and terminology employed herein isnot to be construed as limiting and is for descriptive purpose only.

The principles and uses of the teachings of the present invention may bebetter understood with reference to the accompanying description,figures and examples.

It is to be understood that the details set forth herein do not construea limitation to an application of the invention. Furthermore, it is tobe understood that the invention can be carried out or practiced invarious ways and that the invention can be implemented in embodimentsother than the ones outlined in the description below.

It is to be understood that the terms “including”, “comprising”,“consisting” and grammatical variants thereof do not preclude theaddition of one or more components, features, steps, integers or groupsthereof and that the terms are not to be construed as specifyingcomponents, features, steps or integers.

The phrase “consisting essentially of”, and grammatical variantsthereof, when used herein is not to be construed as excluding additionalcomponents, steps, features, integers or groups thereof but rather thatthe additional features, integers, steps, components or groups thereofdo not materially alter the basic and novel characteristics of theclaimed composition, device or method.

If the specification or claims refer to “an additional” element, thatdoes not preclude there being more than one of the additional element.

It is to be understood that where the claims or specification refer to“a” or “an” element, such reference is not to be construed as therebeing only one of that element.

It is to be understood that where the specification states that acomponent, feature, structure, or characteristic “may”, “might”, “can”or “could” be included, that particular component, feature, structure,or characteristic is not required to be included.

Where applicable, although state diagrams, flow diagrams or both may beused to describe embodiments, the invention is not limited to thosediagrams or to the corresponding descriptions. For example, flow neednot move through each illustrated box or state, or in exactly the sameorder as illustrated and described.

Methods of the present invention may be implemented by performing orcompleting manually, automatically, or a combination thereof, selectedsteps or tasks.

The term “method” refers to manners, means, techniques and proceduresfor accomplishing a given task including, but is not limited to thosemanners, means, techniques and procedures either known to, or readilydeveloped from known manners, means, techniques and procedures bypractitioners of the art to which the invention belongs.

The descriptions, examples, methods and materials presented in theclaims and the specification are not to be construed as limiting butrather as illustrative only.

Meanings of technical and scientific terms used herein are to becommonly understood as by one of ordinary skill in the art to which theinvention belongs, unless otherwise defined.

The present invention can be implemented in the testing or practice withmethods and materials equivalent or similar to those described herein.

The terms “bottom”, “below”, “top” and “above” as used herein do notnecessarily indicate that a “bottom” component is below a “top”component, or that a component that is “below” is indeed “below” anothercomponent or that a component that is “above” is indeed “above” anothercomponent as such directions, components or both may be flipped,rotated, moved in space, placed in a diagonal orientation or position,placed horizontally or vertically, or similarly modified. Accordingly,it will be appreciated that the terms “bottom”, “below”, “top” and“above” may be used herein for exemplary purposes only, to illustratethe relative positioning or placement of certain components, to indicatea first and a second component or to do both.

The core section of an embodiment of a punching system 100 isschematically illustrated FIG. 1 and FIG. 2.

According to some embodiments of the invention, punching system 100 hasa system axis X defining a forward to rear direction, and includes anaxially extending mandrel 15 that passes through a housing 17. The rearend of the mandrel 15 (see FIG. 4) is attached to a machine frame. Thesystem 100 has a punch 11 that is substantially concentric with acounter die 14 of the system 100. Punch 11 and counter die 14 extendalong a punch axis P that is substantially perpendicular to the systemaxis X.

According to some embodiments of the invention, a push bar 16 of thesystem 100, located within mandrel 15, when in a rearward retreatposition, enables punch 11 to be located inside mandrel 15. The rear endof the push bar 16 (not shown in FIGS. 1 and 2) is mechanically coupledto an output of a power unit 30, as schematically illustrated in FIG. 4.

According to some embodiments of the invention, a tube 22 to be punched,which is free to move along the axis X, is located about mandrel 15.Tube 22 having a radius Rt is optionally of a type used in solarheating, air conditioning and other fluid conduction system. Tube 22 forexample may be made of copper, brass, aluminum or stainless steel.

Actuating wedge 19 of the system 100 (wedge 19 seen in FIGS. 1 and 2)which is not in contact with tube 22 is adapted to bias mold 13 alongthe punch axis P inwards towards the mandrel 15 and outwards away formthe mandrel 15. This is optionally performed by key 50 of wedge 19 beingurged to slide within key-way 51 of mold 13. Key 50 and/or key-way 51are angled in relation to the punch axis P and thereby movement of wedge19 towards axis P and away from axis P urges mold 13 to be biased alongthe axis P. The movement of wedge 19 is perpendicular to the punch axisP. It is noted that as mold 13 is biased towards the tube 22 and abutsthe tube 22, it fixes the location of tube 22 along the axis X therebytemporarily disabling the tubes free movement along the axis X duringpunching. In addition it is noted that other mechanisms may be used tobias mold 13 towards and away from the tube 22. Yet further it is notedthat instead or in addition to wedge 19, a biasing mechanism (not shown)may he used to displace tube 22 away and towards the mold 13. Duringpunching the biasing mechanism biases the tube towards the mold andafter punching the biasing mechanism biases the tube away from the moldto enable the tube to be axially displaced so it can be punched atanother location.

When mold 13 moves out, it drags with it counter die 14, which isconstantly inwardly loaded by a biasing means such as, for example,spring 18. Other loading mechanism may be employed. At a predeterminedposition of tube 22, a punching operation is carried out. FIG. 2schematically illustrates the position of tube 22 where punching isperformed. In the punching process, mold 13 is biased towards tube 22 byactivating actuating wedge 19 and thereby imposes a counter force uponthe outer face of the tube. During said process, counter die 14 isadjacent to tube 22 and push bar 16 moves forwardly so as to urge punch11 to go outwardly to pierce the tube 22.

Attention is additionally drawn to FIG. 3. Counter die 14 has an axiallyextending internal cavity that opens out to an inner end of die 14 at anaperture 60. During the outward movement of punch 11, cutting edge 12 ofpunch 11 cuts the wall of tube 22 to produce a corresponding scrap 20(see FIG. 2) that falls down and outwardly. In some cases scrap 20 willcompletely detach from tube 22 and thereby fall down as punch 11 meetscounter die 14 with its cutting edge 12 passing through aperture 60 tobe snugly received within the cavity of die 14. By continuing thisoutward movement, punch 11 flares the wall of tube 22, draws it betweenitself and cavity 10 of mold 13, thereby generating a collar 53 that hasa substantially cylindrical shape that ends at a rim 25 (FIG. 5A).Cavity 10 of mold 13 has a diameter Dc.

In an embodiment, cutting edge 12 of punch 11 has an elliptical shapewith major axis extending along the system axis X. It is noted that theshape of cutting edge 11 affects the curvature of rim 25 as viewed in across section that includes the system and punch axes X, P (FIG. 5A).The closer cutting edge 12 is to a circle the larger the curvature ofrim 25 is in that view; and the closer cutting edge 12 is to an ellipsethe smaller the curvature of rim 25 is in that view. The inventor hasfound that an elliptical or substantially elliptical shaped cutting edge12 forms a rim 25 with a curvature that is favorable for attachment tolateral tubes. Such a rim 25 may differ from a straight line byoptionally up to 1 millimeter or preferably up to 0.5 millimeters asviewed in a cross section including the system and punch axes X, P (FIG.5A).

Attention is additionally drawn to FIGS. 5A and 5B. It is noted thatmold 13 provides a counter force that assists in the formation of acollar 53 with a structure that is well adapted to connect to lateraltubes that may be brazed or connected thereto. A ridge 54 (FIG. 3) wherecavity 10 of the mold 13 opens out of mold 13 inwardly towards the tube22 has a radius R that forms a substantially corresponding externalradius R2 at a join 55 between collar 53 and tube 22.

By way of a numerical example; radius R2 as measured in a cross sectionthat includes the system and punch axes X, P (see FIG. 5A); may have thefollowing dimensions. Optionally R2<1 millimeter, preferably R2≦0.8millimeter, and further preferably R2≦0.5 millimeter. The inventor hasfound that a tube in accordance with an embodiment of the inventionhaving the above R2 dimensions is better adapted for attachment tolateral tubes.

An imaginary cylinder C having a diameter equal to diameter Dc of cavity10 is defined as located about the punch axis P (see FIG. 5B) and animaginary curve 23 is located at the intersection of cylinder C and theouter surface of tube 22 around collar 53. It is noted that in planesperpendicular to the system axis X, curve 23 is located a distancesubstantially equal to Rt from the system axis X which in other wordsmeans that the outer surface of tube 22 maintains its cylindricalgeometry adjacent collar 53. This geometry adjacent collar 23, which theinventor has found as favorable for attachment to lateral tubes, is dueto tube 22 being pressed against ridge 54 of mold 13 during punching.

It is noted that tubes being punched by systems not having a mold 13 mayexhibit deviations larger than 1 millimeter along their correspondingcurves 23 that may affect the quality and strength of attachment of suchtubes to lateral tubes. In addition it is noted that mold 13 enablestubes 22 with a wider range of hardness to be punched in the system 100.For example, tubes made of copper having a tensile strength of up to 400[Newton/mm̂2] may be successfully punched in a system in accordance withthe present invention due to the tube being pressed against mold 13during punching. Punching systems that do not include a mold, upon whichthe tube is biased during punching, may exhibit the formation of cracksin the collar when punching for example copper tubes having a tensilestrength as low as 300 [Newton/mm̂2]. It is noted that tubes havinghigher tensile strengths are cheaper therefore the usage of mold 13 inthe system 100 enables cheaper material to be punched in the system 100.Mold 13 in addition serves as a guiding means for punch 11 as it entersits cavity 10. This guiding function of mold 13 has been found toincrease the number of times punch 11 may be used in the system 100.

Design of system 100 can be numerous. In some embodiments of theinvention, a power pack 30 is located at the rear end of system 100(FIG. 4) or at any other suitable location in the system 100.

According to some embodiments of the invention, at this point, the rearend of mandrel 15 is mechanically coupled to a machine frame 31 and anactuator 27 moves push bar 16 that axially moves inside mandrel 15. Theactuator is connected to the push bar via, e.g., coupling 26. It isnoted that the axial movement of push bar 16 may be provided by variousmeans. For example, the push bar may be actuated to move by hydraulicmeans, elect mechanical means etc. In addition it is noted that suchmeans may be in some embodiments located within the manadrel 15.

While the invention has been described with respect to a limited numberof embodiments, these should not be construed as limitations on thescope of the invention, but rather as exemplifications of some of theembodiments. Those skilled in the art will envision other possiblevariations, modifications, and programs that are also within the scopeof the invention. Accordingly, the scope of the invention should not belimited by what has thus far been described, but by the appended claimsand their legal equivalents. Therefore, it is to be understood thatalternatives, modifications, and variations of the present invention areto be construed as being within the scope and spirit of the appendedclaims.

1. A method for punching at least one hole in a tube comprising thesteps of: providing a system comprising a punch and a mold, placing thetube on the system such that the tube extends along a system axis, thepunch is located within the tube and the mold is located outside of thetube; biasing the punch along a punch axis which is transverse to thesystem axis to make a hole in a wall of the tube; wherein at least aportion of the wall adjacent the hole is pressed between the punch andthe mold to form a collar.
 2. The method according to claim 1, whereinthe collar is formed about the punch axis.
 3. The method according toclaim 1, wherein during the biasing of the punch to make the hole themold at least partially abuts the wall of the tube from the outside. 4.The method according to claim 1, wherein the mold comprises a cavitythat extends along an axis substantially coaxial with the punch axis andopens out towards the tube, wherein at least a portion of the punchenters the cavity when making the hole in the tube.
 5. The methodaccording to claim 4, wherein the at least portion of the wall adjacentthe hole that forms the collar is pressed between the punch and thecavity of the mold.
 6. The method according to claim 1, wherein thesystem comprises a counter die and at least a portion of the counter dieis located within the cavity of the mold.
 7. The method according toclaim 6, wherein the system comprises a biasing means that constantlybiases the counter die towards the tube.
 8. The method according toclaim 6, wherein at least a portion of the wall of the tube is pressedbetween the punch and the counter die when forming the hole.
 9. Themethod according to claim 1, wherein the external faces of the collarand tube merge via a radius.
 10. The method according to claim 9,wherein in a cross section including the system and punch axes, theradius is smaller than 1 millimeter.
 11. The method according to claim9, wherein in a cross section including the system and punch axes, theradius is smaller than 0.8 millimeter.
 12. The method according to claim9, wherein in a cross section including the system and punch axes, theradius is smaller than 0.5 millimeter.
 13. A system for forming at leastone hole in a tube, the system comprising a punch and a mold, the tubewhen placed on the system extending along a system axis, the punch beinglocated within the tube and being adapted to move along a punch axisthat is transverse to the system axis, the mold being located outside ofthe tube.
 14. The system according to claim 13, wherein the moldcomprises a cavity that extends along an axis that is substantiallycoaxial with the punch axis.
 15. The system according to claim 14,comprising a counter die wherein at least a portion of the counter dieis located within the cavity.
 16. The system according to claim 15,comprising a biasing means that constantly biases the counter dietowards the tube.
 17. The system according to claim 13, wherein thepunch comprises an elliptical cutting edge wherein the major axis of theellipse extends along the system axis.
 18. The system according toclaims 13, wherein the mold is adapted to be biased towards and away ofthe tube.
 19. The system according to claim 15, wherein the counter diecomprises a cavity extending along an axis substantially coaxial withthe punch axis.
 20. The system according to claim 19, wherein the punchcomprises a cutting edge, the cutting edge being adapted to be receivedwithin the cavity of the counter die.